Compressor unloader



Patented Mar. 10, 1931 UNI o STATES are-w orrics- WILLIAM E. -1VIATI-IEWS, OF BIRMINGHAM, ALABAMAyASSIGN OR TO I-IARDIE-TYNES MANUFACTURING COMPANY, A CORPORATION OF ALABAMA COMPRESSOR UNLOADER Application filed July 23,

My invention relates to operating means for valves, more particularly for compressor valves, and has for its object the provision of simple effective means for operating such valves either manually or in response to-pressure.

A further-object of my invention is to provide unloader means for a compressor valve including a pressure actuated piston and wherein valve means are embodied in the piston to obviate the necessity of packing the piston.

A still further object of my invention is to provide unloader means for a compressor valve including a pressure actuated piston having valve portions thereon, and wherein means are provided for cushioning the movements of the piston.

The usual mechanism for unloading air compressors, as is well known, comprises some means to hold the inlet valves of the compressor cylinders open during the compression stroke of the piston. In such mechanism it is usual to provide both pressure and manual operating means. Difficulties have been encountered in the design of such apparatus by reason of the heretofore common practice of providing packing for the pressure actuated member which, after being installed and in service for a period of time,

begins to leak and render the operation of the apparatus erratic. Furthermore, it has heretofore been regarded necessary to provide packing around the stem of the manually operable means for the unloading mechanism to prevent leakage around the stem and this packing soon becomes worn andrequires renewal. I

These and other difficulties are overcome by means of my invention, wherein I have provided a pressure actuated unloader piston without packing and having valve portions formed on the piston and cooperating with its cylinder walls to prevent leakage thereby when the piston is at either limit of its travel. In order that the valve portions or their seats may not become damaged by pounding, I provide novel and effective means for cushioning the movements of the piston. Manually operable means is also provided to I range 1928. Serial .No. 294,907.

Fig. 2 is a detail sectional view of a part of the manually operable mechanism.

Referring to the drawing for a better understanding of my invention, 1 show a fragment of a compressor cylinder 10 having an inlet passage 11 along the wall thereof and having a wall provided with a shouldered recess 12for the reception of an inlet valve 13, said valve being of the ring plate type and embodying a plurality'of ring plates l lheld against their seatsby springs 16, only one of V which is shown.

In the outer wall of the inlet passage 11 is provided an opening 17 over which is secured a valve bonnet 18. The valve bonnet 18 has a threaded opening 19 therein for receiving a cylindrical casing 21. The casing 21 is hollow and has positioned therein an unloader piston 30, said piston having a limited of reciprocable movement Within the casing. The lower end of the casing. 21 is provided with a flange-22 and bearing against the flange22 is an outwardly threaded sleeve 23 fitting loosely over the casing 21 and screwing into theopening 19 to hold the casing in place. The sleeve 23 is locked in position by means of a lock nut 24 screwed on over the sleeve and bearing against the valve bonnet.

The valve 13 is held in place by means of a keeper 26 terminating in a ring 27 which bears against the valve 13. The upper end of the keeper 26 is in the form of a ring With a cylindrical bore 28 in alignment with the boreof the casing 21 and having a bushing 29 interposed therein between the lower end of the casing 21 and the keeper 26. The bore 28 is of such Size that the flange 22 of the casing 21 fits snugly therein and thus serves to center the keeper with respect to the casing.

Disposed within the lower end of the casing 21 is a piston 30. The piston 30 is provided, at its upper end, with a beveled valve portion 31 and the casing 21 is bored to form a seat 32 against which'the valve 31 rests when the piston is in its upper position. Thepiston 30 is also provided, at its lower end, with a valve portion-33 which fits against the bushing 29 when the piston is in its lower position. Thus, in either position of the piston, leal iage thereby is prevented and no "packln'g 1S required therefor. p

The lower end of the piston is provided avith an inwardly :extendingstem portion 36 and the bore ofthe bushing 29 is made'of :a size to provide asmooth sliding fit forthe stem portion36. The lower end-of the stem 36 is threaded asat 37and anzoper-ating fork 38 is-screwed on to the lower end thereof. The operating fork'38 has :its upper portion turned to form a piston portion 39 which fits snugly in the lower end of the bore of :the

- keeper 26. The operating fork 38is provided at its lower end with fingers 41 which :are adapted to bearagain-st-the ring plates 14 to hold the valve open. It will be:see11,-upon movements of the piston '30, that there is a small air pocket 42 betweenthe pistomportion 39 and the bushingr29 forming a dash pot and cushioningithe movements of the piston, thus preventing damage .to the valveportions of the piston andtheir seats.

In order that .air entrapped beneath the piston-30 shall not interfere with itsaction in openingthe valve 13, I provide relief ports 43 through thewall of the keeper :26 and extending through-the bushing 29, the bushing 29 being grooved at 44 so that there is always communication through the keeper and through the bushing with theside of the piston stem 36. The piston stem 36 is'turnedto provide a groove 45-around it andwhich extends upw-ardlyitolthe lower-valve portion :33.

In order that the fingers 41 of the operating fork 38 shall :not bear against the ring plates l4except in opening the valve, Iprovide-a spring-46 between the lower end of the piston stem 36 and the valve 13, the valve 13 being provided witha recess 47 for positioning the lower end of the spring. Air for operation of the piston 30 is admitted'atithe upperend of the casing through'a conduit 48.

The piston 30 is made hollow at itsupper enchthe hollow thereof being provided with a shoulder51. Fitting loosely within the hollow of the piston is=a rod 52 which-extends upwardly and is provided, near its upper end, with an elongated hole 53. Extending throughthe hole 53 and into the wall of the casing is a pin 54 which holds theyrod against rotary movement while the elongated hole permits the rod a limited longitudinal move ment. Surrounding the rod 52 nearits upper end is a collar 56 which acts as an abutment for a spring 57 disposed between the collar 56 and the shoulder 51 in the hollow of the piston. The collar 56 is held in fixed position by the pin 54 as may be more clearly seen in Fig. .2. It is made sufiiciently thin to provide ample clearanceiaround it for passage of pressure to operate the piston 30.

The spring 57 is employed where the unloader is used with valves -operating with pressure higher than atmospheric pressure, such, for example, as the high pressure inlet 'valves'of a multi-stage compressor. here lower end ofthe-stem 63 is hollowed out to receivetheupperiturned end-64=of the rod52 which thereby maintains the rod and the .stem in alignment. :Disposed between the collar 56and the -pin 61 is a spring 65 which bears the :weightof the manually operable I;

mechanism -:and :hOldS the rod 52-normally away from the piston 30:2LI1Cll10ltlS the stem 63 in its upper position.

The stem 63, where it projects through the easing:21,'is2provided with a beveled valve portion 66 which seats against a :seat 67 formed in'the outer iendofthe casing, thereby obviating the necessity of packing the stem 63,wthe pressure within the casing holding the valve on the seat. At the upper end of'the TY stem'63 ismounted a balanced handle havingrasector68 out out on its underside which cooperates withia ipin 69'zprovided in'the casing :21 to limit therange of movement of the handle 67.

From the foregoing description the operation ofniy invention will be readily understood. V fihen 'pressure'is admitted to the 'ca'sing2l through (the conduit 48 it forces the "piston 30 downwardly so that the valve :portion 33 seats against the bushing 29,-preventing leakage of air :past the piston and forcing the operating fork 38 downwardly withithe fingers 41 to push the ring plates 14 off their seats. At the same time, air beneath the'ipisto-n 30 passes outwardly through the'portsr43 into the inlet passage 11. When pressure is released from abovethe piston 30, the spring 46 .pushes the unloading fork 35) and piston.30 upwardly until the valve portion 31 is againstltheseat Tfthe pressure in theiinlet passage 11 be above atmospheric, the valve :portion 31 seals the piston against leakage. Thus, withthis arrangement, the pistonBO-may be a relatively loose fit, Without danger of leakage, and be quickly responsive to pressure operation.

Whenever it is desired to operate the device manually, the handle 70 is turned to bring the cam surfaces 61 and 62 carried by the rod 52 and stem 63, respectively, into op,- erative relation to force the rod downwardly against the piston 30, causing the piston to move downwardly and again open the valve. In order to permit the valve to again close, the handle 70 is turned in the opposite direction to move the cam 62 away from the pin 61 whereupon the spring 46 again raises the piston 80 and carries the operating fork 38 upwardly away fro-m the rin plates. At the same time the spring 65 holds the valve portion 66 of the stem 63 against its seat 67.

From the foregoing, it will be apparent that I have devised an apparatus for manual and pressure actuated operation of a compressor unloader which is simple of design and reliable in operation and which may remain in service for an indefinite period of time without necessity of repairing.

Vhile l have shown my invention in but one form, it will be obvious to those skilled in the art that it is not so limited but is susceptible of various changes and modifications without departing from the spirit thereof and I desire therefore that only sucl limitations shall be placed thereupon as are imposed by the prior art or as are specifically set forth in the appended claims.

lVhat I claim is:

1. A device for opening and closing. the unloading valve of a compressor, comprising a casing, a pressure opera-ted piston mounted for reciprocable movement within the casing and having valve portions on the opposed sides thereof, means for supplying pressure to operate the piston, means forming seats for the valve portions and adapted to prevent leakage of pressure by thepressure operated piston when seated, and an operating fork connected directly to the piston and extending to the valve for transmitting movements of the piston to the valve.

2. A device for opening and closing valves in the unloading of compressors, comprising a casing, a pressure operated piston mounted for reciprocable movement within the casing and having valve portions on the opposed sides thereof, means for supplying pressure to operate the piston, means forming seats for the valve portions and adapted to prevent leakage of pressure by the piston when seated, a stem on the piston projectin in wardly from the casing, an operating fork secured to the stem totransmit movement of the piston to the valve, a piston member carried by the fork, a cylinder for the piston member to cushion the movements of the piston, and means pro *ided to release medium entrapped beneath the piston upon movement thereof in a direction to open the valve.

8. Ina device for operating compressor valves, a casing embodying a cylinder, an operating piston in the cylinder, valve portionsformed on the opposed faces of the operating piston, means providing seats for the valve portions of the operating piston to prevent leakage thereby when seated, an inwardly projecting stem on the operating piston, an unloading fork connected to the stem, compressor valve members operated by the fork, adash pot piston on the fork, a cylinder for the dash pot piston to cushion movements of the operating piston upon actuation thereof, and means to admit air to the casingon the outer side of the operating piston for actuation of the latter. V

4. In anlunloader apparatus for a compressor valve, a valve housing having a recess for positioning the compressor valve, a valve bonnet arranged outwardly of the recess and having a threaded opening coaxially therewith, a hollow casing having a cylindrical bore therein extending through the opening and having, a flange on its inner end, a threaded sleeve surrounding the cas ing and screwed into the opening to bear against the flange, a valve keeper interposed between the casing and the valve and forced against the compressor valve by the casing,

vsaid keeper having a cylindrical bore in alignment with'the bore in the casing and receiving the flange of the casing, a bushing having a reduced bore positioned in the bore of the keeper, a piston having valve means on its opposed faces disposed within the easing and having an extension projecting into the bore of the bushing, an unloader fork secured to the extension and turned to fit the bore in the keeper and to cushion against the bushing, means forming seats for the valve portions of'the piston, and means to admit air for operation of the piston on theouter sidethereof.

5. 'An' operating means for opening and closing compressor valves comprising a cylindrical casing, a pressure actuated piston disposed within the casing, means for transmittingmovements of the piston to the valve, a

rod having one end adapted to bear against the plston, a cam within the casing on the other end of the rod, a manually operable stem projecting outwardlyof the casing, in

alignm'ent with the rod, and a cam provided.

on the inner end vofthestem for cooperating with the cam on the rod to actuatethe latter.

6. An operating means foropening and closing compressor valves comprising a cylindrical casing, a pressure actuated piston disposed within the casing, means for transmitting movements of the piston to the valve, a rod having one end positioned to bear against the piston, a cam. within the casing on the other end of the rod, a manually operable stem projecting outwardly of the casing in alignment with the rod, a cam provided: on 3 he inner end of the stem for cooperating with l i on the rod to actuate the latter, a houlder on the stem forming a valve where he stein projects through the casing, and a seat formed on the inner side of the casing cooperating with the shoulder to prevent leakage thereby outwardly of the casing.

7. An operating means for opening and closing compressor valves comprising a cylindrical cits v a pressure actuated piston disposed with n the casing, means for transmitting movements of the piston to the valve, a rod having one end adapted to bear against the piston, afcam within the casing on the other end of the rod, a manually operable stem projecting outwardly of the casing, a can provided on the inner end of the stem for cooperating with the cam on the rod to actuate the latter, means for maintaining the stem and the rod in alignment, means for holding the rod against rotary movement, a shoulder on the stem forming a valve where the stem projects through the casing, and a seat formed on the inner side of the casing 00- operating with the shoulder to prevent leakage thereby outwardly of the casing.

8. An operating means for opening and closingcompressor valves comprising a cylindrical casing, a hollow pressure actuated piston disposed within the casing, means for transmitting movements of the piston to the valve, a rod having one end fitting in the hollow of the piston, a cam within the casing on the other end of the rod, a manually operable stem projecting outwardly of the casing, a cam provided on the inner end of the stem for cooperating with the cam surface of the rod to actuate the latter in a direction to open the valve, sp ing means for closing the valve when the stem is turned in a direction to separate the cams, means for maintaining the stem and the rod in alignment, means for holding tl e rod against rotary movement, a shoulder on the stem forming a valve Where the stem projects through the casing, and a seat formed on the inner side of the casing cooperating with the shoulder to prevent leakage outvsa rdly of the casing.

9. An operating means for opening and elosin g compressor valves comprising a cylindrical casing, hollow pressure actuated piston disposed within the casing, means for transmitting movements of the'piston, a rod having one end fitting in the hollow of the 3 lston, a cam within the casing on the other end of the rod, manually operable stem projeeting outwardly of the casing, a cam provided on the inner end of the stem for cooperating with the cam surface of the rod to actuate the latter in a direction to open the valve, spring means for closing the valve when the stem is turned in a direction to separate the cams, means for maintaining the stem and the rod in alignment, means for holding the rod against rotary movement, a shoulder on the \VILLIAM E. MATHEWVS. 

